1. Field of the Invention
This invention relates to a multiple-output power supply apparatus for a vehicle. In addition, this invention relates to a method of controlling a multiple-output power supply apparatus for a vehicle. Furthermore, this invention relates to an apparatus for controlling a vehicular power generator or a vehicular alternator.
2. Description of the Related Art
Japanese patent application publication number P2000-354334A discloses a method of charging a combination battery which has cells coupled together in series. The combination battery has a negative terminal, a first positive terminal, and a second positive terminal. The negative terminal leads from the negative end of the series of the cells. The second positive terminal leads from the positive end of the series of the cells. The first positive terminal is connected with an intermediate tap (a junction) between neighboring two among the cells. Therefore, a voltage (a first output voltage) at the first positive terminal is lower than a voltage (a second output voltage) at the second positive terminal. A first load is connected between the negative terminal of the combination battery and the first positive terminal thereof. Thus, the first load is driven by the first output voltage. A second load is connected between the negative terminal of the combination battery and the second positive terminal thereof. Thus, the second load is driven by the second output voltage. A first power generator acts to charge all the cells in the combination battery. A second power generator acts to charge the cell between the negative terminal of the combination battery and the first positive terminal thereof. A DCxe2x80x94DC converter fed with power from the first power generator is used in correctively or supplementally charging the cell between the negative terminal of the combination battery and the first positive terminal thereof. Accordingly, it is possible to reduce differences in conditions among the cells in the combination battery. The reduction of the differences results in a longer life of the combination battery. The DCxe2x80x94DC converter can be fed with power from the combination battery.
Japanese patent application publication number 10-257682 discloses an apparatus for controlling a combination battery which has cells coupled together in series. The apparatus in Japanese application 10-257682 includes voltage control circuits and DCxe2x80x94DC converters. The voltage control circuits are connected with the cells, respectively. In addition, the voltage control circuits are connected with the DCxe2x80x94DC converters, respectively. The DCxe2x80x94DC converters are connected with the cells, respectively. The DCxe2x80x94DC converters are coupled to each other so that power can be transmitted thereamong. The voltage control circuits activate and deactivate the DCxe2x80x94DC converters in response to the voltages across the cells, respectively. When one of the cells becomes close to an overcharged state and hence the voltage thereacross exceeds a reference level, the voltage control circuit connected with the cell in question activates the related DCxe2x80x94DC converter by using power in the cell in question. The power is transmitted from the activated DCxe2x80x94DC converter to the other DCxe2x80x94DC converters before charging the cells connected with the other DCxe2x80x94DC converters. As a result, power is transmitted from the cell in question to the other cells. In such a way, the voltage control circuits and the DCxe2x80x94DC converters operate to equalize the charging states of the cells.
It is a first object of this invention to provide an improved multiple-output power supply apparatus for a vehicle.
It is a second object of this invention to provide an improved method of controlling a multiple-output power supply apparatus for a vehicle.
It is a third object of this invention to provide an improved apparatus for controlling a vehicular power generator (a vehicular alternator).
A first aspect of this invention provides a multiple-output power supply apparatus for a vehicle. The apparatus comprises a lower battery block for feeding low-voltage power to a low-voltage load, the lower battery block including cells; at least one higher battery block connected in series with the lower battery block and cooperating with the lower battery block to feed high-voltage power to a high-voltage load, the higher battery block including cells; power generator means for feeding power to a combination of the lower battery block and the higher battery block; a DCxe2x80x94DC converter for transmitting power from the higher battery block to the lower battery block; and controller means for detecting an electric parameter of the lower battery block which relates to an average per-cell voltage in the lower battery block, for detecting an electric parameter of the higher battery block which relates to an average per-cell voltage in the higher battery block, for comparing the detected electric parameter of the lower battery block and the detected electric parameter of the higher battery block, and for controlling the DCxe2x80x94DC converter to equalize the average per-cell voltage in the lower battery block and the average per-cell voltage in the higher battery block in response to a result of said comparing.
A second aspect of this invention is based on the first aspect thereof, and provides a multiple-output power supply apparatus further comprising a first cell equalizing circuit (a first cell voltage (SOC) balancer circuit) connected with the cells in the lower battery block and equalizing voltages across the cells in the lower battery block; and a second cell equalizing circuit (a second cell voltage (SOC) balancer circuit) connected with the cells in the higher battery block and equalizing voltages across the cells in the higher battery block.
A third aspect of this invention provides a method of controlling the multiple-output power supply apparatus of the second aspect thereof. The method comprises the steps of waiting until operation of the first cell equalizing circuit and operation of the second cell equalizing circuit are completed; and operating the DCxe2x80x94DC converter under a condition that operation of the first cell equalizing circuit and operation of the second cell equalizing circuit have been completed.
A fourth aspect of this invention provides a method of controlling the multiple-output power supply apparatus of the first aspect thereof. The method comprises the steps of detecting a first general parameter relating to one of (1) a SOC (state of charge) of the lower battery block, (2) the average per-cell voltage in the lower battery block, and (3) a current fed from the lower battery block to the low-voltage load; detecting a second general parameter relating to one of (1) a SOC of the higher battery block, (2) the average per-cell voltage in the higher battery block, and (3) a current fed from the higher battery block to the high-voltage load; operating the DCxe2x80x94DC converter in cases where the detected first general parameter is smaller than the detected second general parameter by greater than a first threshold value; and maintaining operation of the DCxe2x80x94DC converter during a prescribed time interval after a difference between the detected first general parameter and the detected second general parameter becomes less than the first threshold value, or maintaining operation of the DCxe2x80x94DC converter until the difference between the detected first general parameter and the detected second general parameter becomes less than a second threshold value smaller than the first threshold value.
A fifth aspect of this invention provides a method of controlling the multiple-output power supply apparatus of the first aspect thereof. The method comprises the steps of detecting a first general parameter relating to one of (1) a SOC of the lower battery block, (2) the average per-cell voltage in the lower battery block, and (3) a current fed from the lower battery block to the low-voltage load; detecting a second general parameter relating to one of (1) a SOC of the higher battery block, (2) the average per-cell voltage in the higher battery block, and (3) a current fed from the higher battery block to the high-voltage load; and intermittently activating the DCxe2x80x94DC converter in cases where the detected first general parameter is smaller than the detected second general parameter by greater than a prescribed threshold value.
A sixth aspect of this invention is based on the fifth aspect thereof, and provides a method further comprising the step of continuously activating the DCxe2x80x94DC converter in cases where the detected first general parameter is smaller than the detected second general parameter by greater than a given threshold value, the given threshold value being greater than the prescribed threshold value.
A seventh aspect of this invention provides a method of controlling the multiple-output power supply apparatus of the first aspect thereof. The method comprises the steps of calculating a first apparatus operation efficiency which occurs if the DCxe2x80x94DC converter is continuously activated; calculating a second apparatus operation efficiency which occurs if the DCxe2x80x94DC converter is intermittently activated; and intermittently activating the DCxe2x80x94DC converter in cases where the calculated second apparatus operation efficiency is higher than the calculated first apparatus operation efficiency.
An eighth aspect of this invention provides a method of controlling the multiple-output power supply apparatus of the first aspect thereof. The method comprises the steps of determining whether or not a vehicle engine ignition switch is in its OFF position; and operating the DCxe2x80x94DC converter for every prescribed time interval per prescribed term in cases where the vehicle engine ignition switch continues to be in its OFF position.
A ninth aspect of this invention provides a method of controlling the multiple-output power supply apparatus of the first aspect thereof. The method comprises the steps of determining whether or not a speed of the vehicle is lower than a preset speed; setting a power output from the DCxe2x80x94DC converter to a first power level when the speed of the vehicle is lower than the preset speed; and setting the power output from the DCxe2x80x94DC converter to a second power level when the speed of the vehicle is not lower than the preset speed, the second power level being greater than the first power level.
A tenth aspect of this invention provides an apparatus for controlling a vehicular power generator. The apparatus comprises power storage means; a power generator for feeding power to the power storage means and an electric load; and controlling means for intermittently activating the power generator to approximately equalize an average power output from the power generator to a power consumed by the electric load.
An eleventh aspect of this invention is based on the tenth aspect thereof, and provides an apparatus further comprising means for detecting a rotational speed of a drive shaft of the power generator, and means for, during the intermittent activation of the power generator, controlling the power generator in response to the detected rotational speed of the drive shaft of the power generator on the basis of a predetermined relation among the rotational speed of the drive shaft of the power generator, a power generation efficiency of the power generator, and a power output from the power generator to provide an instantaneous power output corresponding to a high power generation efficiency.
A twelfth aspect of this invention is based on the tenth aspect thereof, and provides an apparatus wherein the controlling means comprises first sub-means for calculating a first total energy efficiency which occurs if the power generator is intermittently activated, second sub-means for calculating a second total energy efficiency which occurs if the power generator is continuously activated, third sub-means for intermittently activating the power generator when the first total energy efficiency is higher than the second total energy efficiency, and fourth sub-means for continuously activating the power generator when the second total energy efficiency is higher than the first total energy efficiency.
A thirteenth aspect of this invention is based on the twelfth aspect thereof, and provides an apparatus wherein the controlling means comprises means for calculating the first and second total energy efficiencies from a power generation efficiency of the power generator and charging and discharging efficiencies of the power storage means.
A fourteenth aspect of this invention is based on the tenth aspect thereof, and provides an apparatus wherein the controlling means comprises first sub-means for determining whether or not a vehicle is decelerating, second sub-means for operating the power generator at a maximum power output when the first sub-means determines that the vehicle is decelerating, and third sub-means for intermittently activating the power generator when the first sub-means determines that the vehicle is not decelerating.
A fifteenth aspect of this invention is based on the tenth aspect thereof, and provides an apparatus wherein the controlling means comprises first sub-means for detecting an acceleration of a vehicle, and second sub-means for deactivating the power generator when the detected acceleration of the vehicle exceeds a prescribed value.
A sixteenth aspect of this invention is based on the tenth aspect thereof, and provides an apparatus further comprising means for detecting a parameter relating to one of (1) a SOC of the power storage means and (2) a voltage across the power storage means, means for, during the intermittent activation of the power generator, continuously operating the power generator at a specified power output until the detected parameter rises to a first prescribed value, and means for, during the intermittent activation of the power generator, continuously deactivating the power generator until the detected parameter drops to a second prescribed value lower than the first prescribed value.
A seventeenth aspect of this invention is based on the tenth aspect thereof, and provides an apparatus wherein the power storage means comprises a lithium battery.
An eighteenth aspect of this invention is based on the tenth aspect thereof, and provides an apparatus wherein the power storage means comprises an electric double layer capacitor.